1. Field of the Invention
The present invention relates to a method for the instrumentation of sizes of retinal vessels in the fundus and an apparatus therefor and, more particularly, to a method for the instrumentation of the blood circulation function, specifically, the instrumentation capable of detecting a state of the blood reflux from the state in which the retinal vessels in the fundus vary in correspondence with heart pulses, thus permitting an easy clinical evaluation of the microvasculature circulation.
2. Description of Related Art
The retinal vessels in the fundus are the ones that can be observed directly from the outside so that they are utilized for the internal diagnosis of disorders of circulatory organs, diabetes and so on as well as for the ophthalmologic diagnosis by an ophthalmoscopic or photographic observation.
In order to permit a good circulation, it is important to allow the venous vessels to contract to an appropriate extent and to thereby retain no excessive amount of blood therein. For normal people, as a ratio in size of the arteriola to the venule is approximately 2 to 3, a ratio in size of the arteriola to the venule in the fundus is seen significant for evaluation to judge whether the blood circulation is good and a photography of the fundus is used as a means of testing the blood circulation function. It is noted, however, that sizes of the retinal arteriola and venule vary with heart pulses so that it is difficult in many cases to determine what are sizes of the retinal arteriola and venule at the maximum diastole and thus the conventional technique suffers the disadvantage in terms of a diagnosis accuracy. Currently, this technique is mainly used for observation for a discrepancy of sizes of the arteriola which arises as a symptom develops, and the arteriolae and so on at the stage of a pachynsis of vessel walls or other sclerosis.